There was an anecdote from someone working at Microsoft in the early 2000s. The story says, Microsoft Office code due to legacy reasons stemming from the 90s was incredibly fragile and building it was a no easy feat. Office team had a bunch of carefully maintained build servers with carefully controlled version of Windows, MSVC compiler, and other software. Whenever a new build server was needed, they simply made a copy from an existing one (literally, copying the HDD contents) rather than install a system from scratch.

I heard this story from someone in my uni and I used to laugh at it, because surely having something like this today would be totally ludicrous. Now I see people use Docker and I don't laugh any more.